store a single var in flash and load at start

Hello,

I'm looking for to store a var in a permanent way (power off) and load at start (power on)
i saw that @Gordon implement a way to store data since 2v05, but the example code is for log datas (implementative way) and it seems a beat complex just for store a counter var.

have you a simple example to implement a counter (with a long type) storage over power-down?

I've tried

var memoire = require("Storage");
[...]
let NumPoemeEncours = memoire.read("num"); // numero encours
  if (NumPoemeEncours == null || NumPoemeEncours == undefined  || NumPoemeEncours == "") {
      NumPoemeEncours = 1;
      console.log("numero du poeme inconnu", memoire.read("num"));
      memoire.write("num",NumPoemeEncours);
      console.log("numero du poeme connu", memoire.read("num"));
  }
console.log("NumPoemeEncours:",NumPoemeE­ncours);

but it does not works!

what i'm doing wrong?

thanks for your time.